HIIT- Really the sh*t? Or should I be jogging instead?

At this point, everyone who has an interest in exercising and keeping fit has heard and tried High Intensity Interval Training (HIIT). A study by the American College of Sports Medicine found that it was the second most discussed fitness topics in popular media last year (first place: body weight training). It is easy to see why: in our frenetic modern day lifestyles, a training style which promises all the benefits of exercise in half the time is going to be popular!

For the uninitiated, HIIT is a training technique which asks for short bouts of maximal intensity exercise, followed by a limited rest period. For the fitness nerds out there (welcome to the club): The principle is that the high intensity section of the workout creates a high oxygen demand in your body, which outstrips your body’s ability to get adequate oxygen to the working muscles (anaerobic fitness). This causes your body to continue working and asking your body for more oxygen during the recovery period, leading to an elevated metabolism which can last up to 24 hours after the bout of exercise. Every time you repeat an interval, this effect is extended. This has led to the more sensationalist magazine writers to make cover page claims of being “Bikini Fit by working out just SEVEN MINUTES A DAY” and telling you to “DITCH YOUR RUNNING SHOES” because those long end of day jogs are a waste of your time…

But what does the scientific evidence actually say? Can you get fit with such short workouts? And is HIIT really superior to steady state cardio?

In 2006, Matrin Gibala performed a study looking at exactly this, which was published in the Journal of Physiology. He asked one group of test subjects to cycle as hard as they possibly could for 30 seconds, followed by a 4 minute rest, repeated 6 times. They were asked to do this three times a week. The other group were asked to come in to the lab five times a week, and cycle at a low to medium pace for 60 minutes at a time. The results were noteworthy – when the subjects were tested after 6 weeks, they found no difference between the two groups on measures of muscle metabolism and cardiovascular fitness. Another study in 2010 from Macpherson found similar findings: after six weeks of training three times a week, those in the HIIT group and those in the hour long cardio group lost the same amount of body fat, and gained similar levels in fitness. When you take into account the amount of time committed by the groups to their respective exercise regimes, you can see why people got excited! “I just don’t have time” must be the biggest excuse I hear day in and day out at Radiance with my clients, but here is a way for people to get away with doing less for the same gains.

Is steady state cardio therefore a waste of time? Certainly not! Aerobic exercise like steady state cardio has been an important part of exercise plans since, well, since exercise started getting planned. The benefits it incurs for heart health are unchallenged by any other form of exercise. The sub-maximal intensity allows the heart ventricles to fill completely before pumping blood out of the heart. This leads to larger ventricles and stronger heart muscles. Mentally, steady state cardio also has its place, with researches reporting relaxed, de-stressed participants reporting improved mood and focus after a 45 minute bout of medium paced aerobic exercise. But this seems to be a matter of preference: what may feel meditative to some people may be boring to others.

The advantage of HIIT lies in its efficiency and effectiveness, as well as its ability to be varied and allow a whole body approach. The HIIT principle can be broadly applied to any exercise or area of the body you wish to work on. Sit-ups, lunges, push-ups and body weight squats done maximally for 30 seconds with a short rest in between will help you develop strength in all areas of your body, improve your cardiovascular fitness, and increase your metabolism for hours afterwards. For those interested in training for sports performance (rugby, basketball, football) it is imperative to include HIIT in your training plan.

The drawbacks? Firstly, a lot of people think they are training with high intensity, but they are not. True HIIT requires absolutely maximal effort: gasping for breath and questioning your life choices, not slightly out of breath but still thinking about what to put in your post-workout smoothie. If you don’t achieve the intensity required, you won’t accrue the benefits promised! And for some people, this can lead to an anxiety-like state – they get nervous thinking about exercise. Exercise is supposed to be fun – life is too short for that! Also, the maximal nature of HIIT training can lead to overtraining and injuries, especially for beginners and those not used to the effects of hard training. It is a lot easier and safer for beginners to gradually increase the length and intensity of steady state cardio.

So what is the answer?

As with most things in life, the answer is neither black nor white, and lies somewhere in the middle. Certainly, HIIT does offer you the chance to get a very effective workout done in a short period of time. However, aerobic fitness should not be ignored for a variety or reasons, least of all its long term health benefits. Marathon runners would profit from cross-training to improve their performance, and those who do nothing but ‘kill’ themselves in the gym would benefit from a period of sustained, low intensity cardio efforts.

An effective exercise plan or program, whether designed by yourself or a professional, should have a long term goal. Then, depending on your long term goal, your training should include both steady state cardio efforts, interspersed with periods of HIIT to get to where you need to be. For beginners, I will always begin them on a regime of steady state cardio until their resting heart rate is below 70 – an indicator that their aerobic system is up to scratch, and they are ready to take their training intensity up with the introduction of HIIT. This variation will lead to less injuries, and greater long term gain in both heart health, aerobic capacity, muscle growth, and high intensity exercise capacity.

The short answer? All exercise is good, but the best exercise for you is the one which matches your personality and goals. But don’t be afraid to mix it up, and if you’re not sure how, ask a good fitness professional to help you!

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About the Author

Declan Halpin

Head of Physiotherapy, UFIT

Declan is the Head of Physiotherapy at UFIT Singapore. He holds both a BSc in Sport and Exercise Science from the University of Limerick and an MSc in Physiotherapy from King’s College London. He is dedicated to helping his patients realise their potential, and returning all of them to optimal function in the shortest period of time, whether they’re an international athlete returning to competition, a patient recovering from surgery or a grandparent who wants to play with the grandchildren. He’s passionate about functional exercise rehabilitation, and firmly believes in the importance of exercise as both a form of treatment and prevention for many of the health issues facing modern day society.